Techniques known for augmenting heating/warming capabilities of clothing fabric include adding electric wires to the fabric, typically by incorporating the wires directly into the fabric or by attaching the wires to the fabric, e.g., by sewing. It is also known, e.g., from Gross et al. U.S. Pat. No. 4,021,640, to print an electrical circuit with a resistance-heating element on a sheet of plastic, such as MYLAR(copyright), and to incorporate strips of the plastic sheet into a fabric article, such as a glove.
According to one aspect of the invention, an electric resistance heating/warming composite fabric article comprises at least: a fabric layer having a first surface and an opposite, second surface, and a flexible electric resistance heating/warming element in the form of an electricity-conducting yarn mounted upon the first surface of the fabric layer and adapted to generate heating/warming when connected in an electrical circuit with a power source.
Preferred embodiments of the invention may include one or more of the following additional features. The electric resistance heating/warming element has the form of the electricity-conducting yarn mounted upon the first surface by embroidery stitching upon the first surface. The electric resistance heating/warming element is mounted upon the first surface by securement of the conductive yarn upon the first surface, by adhesion of the conductive yarn upon the first surface, or by mechanical securement of the conductive yarn upon the first surface. The first surface is a flat surface, and the electric resistance heating/warming element is mounted upon the first surface by an overlaying protective layer laminated upon the first surface with the electricity-conducting yarn disposed and secured between the protective layer and the first surface. Preferably, the protective layer comprises plastic film. More preferably, the plastic film is breathable and permeable to moisture vapor, but resistant to passage of air and water droplets. The protective layer comprises fabric. The fabric article is flat with opposite smooth surfaces, or it has a raised surface and an opposite, smooth surface, or it has opposite, raised surfaces. The first surface is a smooth surface laminated with a barrier layer resistant to passage of air and water droplets but permeable to moisture vapor. The first surface is an inner surface or an outer surface, relative to a region to be heated/warmed. The fabric layer is hydrophobic or hydrophilic. The electric heating/warming element has resistivity in the range of about 0.1 ohm/m to 500 ohm/m. The electrical conductor elements are adapted for connecting the electric resistance heating/warming elements to a power source of alternating current or to a power source of direct current, e.g. a battery, which may be mounted to the fabric body. The electric resistance heating/warming composite fabric article further comprises a barrier layer positioned at least adjacent to at least one of the first surface and the opposite, second surface of the fabric layer. The barrier layer may be positioned at least adjacent to, and may be attached upon, the first surface or the opposite, second surface of the fabric layer. The barrier layer is hydrophobic porous, e.g., comprising poly tetra fluoro ethylene (PTFE), or the barrier layer is non-porous hydrophilic, e.g., comprising polyurethane. The electric resistance heating/warming element is washable, non-swelling and hydrophobic. The electric resistance heating/warming element is resistant to stiffening and cold crack. The fabric article is a single face raised fabric article, e.g. with the second surface a raised surface, or a double face raised fabric article, with both first and second surfaces raised surfaces.
According to another aspect of the invention, a method of forming an electric resistance heating/warming composite fabric article comprises: providing a fabric layer having a first surface and an opposite, second surface, and mounting an electricity conductive yarn at the first surface of the fabric layer in a predetermined pattern of an electric circuit to form an electric resistance heating/warming element adapted for connection.to a power source, thereby to generate heating/warming.
Preferred embodiments of the method of the invention may include one or more of the following additional features. The method comprises the further step of incorporating the electric resistance heating/warming composite fabric article into articles of apparel, such as jackets, sweaters, hats, gloves, shirts, pants, socks, boots, and shoes, and/or into home furnishings textile articles, such as blankets, throws and seat warmers. The method comprises the further step of connecting the electric resistance heating/warming element to a power source, thereby to generate heating/warming. The electricity conductive yarn forming the electric resistance heating/warming element comprises one or more of: a core of insulating material, an electrical conductive heating element disposed generally about the core, and a sheath material generally surrounding the electrical resistance heating element and the core, and the method may comprise the further step of forming the sheath material by wrapping the electrical conductive heating element and the core with yarn. The method comprises the further step of connecting the electric resistance heating/warming element to a source of electric power, e.g. alternating current or direct current, e.g., in the form of a battery, and generating heat. The battery may be mounted to the fabric article. The method further comprises the steps of: positioning a barrier layer adjacent to or attached upon at least one of the first surface of the fabric layer and the opposite, second surface of the fabric layer.
Objectives of this invention include providing an electric resistance heating/warming composite fabric article that may be stretchable, making it comfortable to wear, flexible, washable, non-swelling and/or hydrophobic. In embodiments of the invention including a barrier layer associated with or attached to the fabric layer, the electric resistance heating/warming composite fabric article may be waterproof, but also vapor permeable, making it particularly suited for use in winter garments.